1. Field of the Invention
The present invention relates to a sheet post-processing apparatus that performs post-processing for sheets discharged from image forming apparatuses such as a copying machine, a printer, and a multifunction peripheral.
2. Description of the Related Art
Among image forming apparatuses (hereinafter referred to as MFPs), there is an MFP in which a sheet post-processing apparatus is provided adjacent to a paper discharging unit of an MFP main body in order to perform sheet post-processing for subjecting sheets after image formation to sort processing, staple processing, or the like.
In the sheet post-processing apparatus, a standby tray that subjects a sheet to buffering in the middle of a conveying path of the sheet post-processing apparatus is provided in order to adjust sheet discharge timing from the MFP and sheet post-processing timing to each other. In performing post-processing, there is a step of dropping sheets from the standby tray to a processing tray that aligns the sheets with respect to a processing device such as a stapler and performs positioning. In this step, since a movable sheet receiving plate of the standby tray opens in a direction perpendicular to a conveying direction, there is a problem in that, when there is no member that supports the center of the sheets and, in particular, the sheets are sheets of a large size such as A3 or LD, the sheets may curve in a V shape and may not fall to the processing tray in a desired shape.
In relation to this problem, an image forming apparatus is proposed in which, for the purpose of stretching a curled sheet at the time of printing, a driving roller having a rotating shaft perpendicular to a conveying direction of sheets is provided and a driven roller that forms a pair with this driving roller and rotates following the driving roller is arranged to obliquely cross the rotating shaft of the driving roller (e.g., JP-A-6-144671).
However, the apparatus in the application described above is not devised on the premise that sheets are dropped from a standby tray to a processing tray. Thus, it is impossible to solve the problem simply by providing this apparatus.